As is known, handlers serve to feed electronic components, such as ICs for example, to a test head of a test device, so as to contact the components with the test head and subject these to electrical tests. If the components are to undergo acceleration tests, the component tempered as required is conveyed to a nest, contacted with the test device and accelerated, for example, in perpendicular direction to the contact plane of the component.
In this respect, a device is expressly designated as a handler even if the components are not conveyed to the nest automatically but the nest is loaded by hand.
For this purpose, as is known, the acceleration device comprises a tappet with a free end, to which the nest can be fixed. The tappet is moved to and fro in the axial direction by a movement generation device. The movement generation device can be in the form of a coil, for example, and work according to the loudspeaker principle.
During such acceleration tests the frequencies may vary from the low hertz range to the kilohertz range. The acceleration distance can be a few micrometers up to several centimeters.
Here, there is a problem that, due to the movement generation device, for example a coil, secondary accelerations in unintended spatial directions and also rotary movements can be transmitted to the tappet and thus to the component being tested, as a result of which the measurement results can be distorted. A further problem is that the bearings for linear guidance of the tappet are exposed to extreme loads by the sometimes very high movement frequencies and by temperature ranges of between −55° C. to +155° C., at which these tests are performed. Standard bearings usually do not withstand such loads and do not have the desired durability.
The technology herein relates to a handler of the type initially specified comprising an acceleration device, which with a simple design avoids unwanted secondary accelerations and/or rotations of the tappet and has high durability.
The tappet is linearly guided by means of at least one flat spring, comprising two groups of spring arms, one group being fixed to the tappet and the other group to a frame, which is stationary in relation to a housing of the movement generation device.
By means of such a flat spring the tappet can be prevented from being moved or accelerated in unwanted directions. For example, if the tappet is to be moved to and fro in z-direction, the flat spring prevents the tappet from moving in x and y directions or rotating about its longitudinal axis. Because one group of spring arms is securely fixed to the tappet and the other group to the frame, there are no rolling or sliding movements between the tappet and the flat spring on the one hand and the flat spring and the frame on the other hand, so that unwanted heat generation and wear in these areas can be avoided. The flat spring thus ensures very precise, linear guidance of the tappet in the desired direction with little wear and high durability within a small space.
In accordance with an advantageous embodiment each group has two to six, in particular three to five, spring arms. Particularly preferably in this case, there are three to four spring arms per group, since with such a number on the one hand the tappet is precisely supported in all directions transversely to its longitudinal axis and on the other hand the design of the flat spring can be very simple.
In accordance with an advantageous embodiment the spring arms extend at least substantially radially inwards from a circular closed peripheral area. This permits very compact design of the flat spring. Alternatively, however, in principle the one group of spring arms, which is connected to the tappet, can also extend inwards from the circular closed peripheral area and the other group of spring arms, which is connected to the frame, outwards from the circular closed peripheral area. In addition, all spring arms can also extend outwards, for example if the tappet is in the form of a tube and the flat spring is arranged inside the tappet.
Preferably, the peripheral area is of annular form. Alternatively, however, the peripheral area can also have another form, for example a polygonal form.
Preferably, the spring arms are arranged evenly distributed in the circumferential direction of the flat spring. As a result, uniform application of force onto the flat spring and uniform transmission of power from the tappet to the frame are ensured.
The spring arms can be formed in a straight-line or curved, preferably having an S-shaped curved section in the latter case. While straight-line formation of the spring arms permits very simple and economical production of the flat spring, curved spring arms have the advantage that particularly large deflections are possible within a small space, since the length of the spring arms is increased as a result of the curvature.
The S-shaped curved sections of all spring arms can be arranged in parallel. Alternatively, however, the S-shaped curved sections of one part of the spring arms, preferably half of all spring arms, can also be aligned running counter to the S-shaped curved sections of the other part of the spring arms. As a result, possible torques about the longitudinal axis of the tappet, which are generated by the individual spring arms as the tappet moves to and fro, can cancel each other out.
Preferably, the spring arms are connected to the tappet and the frame at fixing places, which lie on a common circle. As a result, the tappet is supported particularly uniformly on all sides.
In accordance with a further embodiment the tappet is linearly guided by means of at least two axially spaced flat springs. Here, a first flat spring can be arranged adjacent to the nest and at least one further flat spring adjacent to the movement generation device either on the same side as the first flat spring or beyond the movement generation device. The radial support of the tappet by several flat springs permits particularly good linear guidance of the tappet in the desired direction. The arrangement of at least one further flat spring beyond the movement generation device is naturally only possible with acceleration devices in which the tappet passes through the movement generation device and projects over its rear.